Black and white audiences alike call him "Denzel" - as if hailing a champion. In his early 50s, he looks magnificent, in a range that moves easily from mischief and hilarity to wrath and tragedy. He is one of the few actors around who already has a lead role acting Oscar (for Training Day) and a supporting actor Oscar, too (for Glory). There might have been others - for The Hurricane, The Siege, Courage Under Fire, Malcolm X, Crimson Tide and Philadelphia. You run those titles from the 90s, and something begins to sink in. "Denzel" may be our living champion, a resplendent actor, but he sure is having a hard time finding worthwhile parts. And what does that say if it doesn't say something about being black in America?

Take his latest big picture, American Gangster, which arrives under the flag of heavy credentials - Ridley Scott as director, Steven Zaillian as screenwriter, and Russell Crowe as his co-star. It's the Frank and Richie story. Frank is this kingpin drug-runner who makes use of the Vietnam war to open up private supply lines with the far east - he is bringing in kilos of pure stuff from the jungle in the coffins that contain American body-bags. Frank becomes the leading figure in New York's heroin trade. He offs people personally, to keep respect, and, of course, he never touches the heroin himself.

Richie is a cop, terrified of public speaking, who wins an early reputation for ridiculous and unmanageable humourlessness by turning in trunkloads of illegal money. So he's an outside figure who earns grudging admiration in the NYPD because of his refusal to ease up on Frank. The day comes when Richie works out how the coffins are loaded and so one morning Frank and his entourage come out of church in Harlem and Richie and 100 cops have the place staked out. It is the first time in the movie that Denzel and Crowe face each other. It is like that dazzling but daft "cup of coffee" scene in Michael Mann's Heat.

The film is almost over. Yet we see the shambling public speaker make the case in court. We get a very well written and played conversation between the two men. And then, as it prepares to exit, the film bursts into sudden, real life. Richie quits the force. He goes into private law practice, as a defending attorney. And his first client is ... Frank! By 1991 he's got Frank out of jail, on parole!

Throughout the film, Frank and Richie (Denzel and Crowe) behave like driven men who do not pause to think about anything they do. This is not conducive to interesting drama or story. And yet, at this magical moment, when two lifelong opponents settle for a natural alliance, the film passes on briskly, not even bothering to wonder, who would be interested in that?

Well, me, I'm interested, and Denzel and Crowe - if they're real actors and not just floating monster pay-days - are going to be interested. I want to see the process whereby the righteous cop realises the legal system is sick and crazy. I want to see the admiration and fellowship grow between two such opponents. Because if you don't show it to me, I'm inclined to say this is the same old bogus runaround we were given in Heat, where two outrageously great and self-satisfied actors played the routine that said: well, really, aren't cops and hoodlums cut from the same cloth? No, they are not, and why do our movies keep trying to insist on the iniquity?

So, hear this cry for Denzel that at his peak he has to play such garbage. It is not too far from the way Washington sometimes plays with white actresses (The Pelican Brief with Julia Roberts, Courage Under Fire with Meg Ryan), but is hardly allowed to touch them. I'll believe in progress the day Denzel Washington plays a black man who has a full-blooded physical love affair with a white woman. And it's promoted as a big picture. It's not his next picture: that's The Great Debaters, in which Denzel plays the man from the 30s who taught kids from a small black school to debate with the stars of Harvard. A worthy subject, as they say, and the reservation available to great black actors.